This study compared inspiratory characteristics of the Novolizer^® and Turbuhaler^®. Sixty patients with obstructive lung disease (40 asthmatics, 20 patients with COPD) and without DPI experience were enrolled into this investigator initiated, randomized, cross-over study. Collected data of 56 patients were eligible for analysis. Inspiratory pressure and inspiratory flow through both devices were measured in every patient using a double-beam oscilloscope. Peak inspiratory flow (PIF), duration of inspiratory flow >60l/min and increase in inspiratory pressure were significantly higher in the Novolizer^® group. In addition, the inspiratory flow rate 0.1s after beginning of inhalation was over two-times higher at inhalation through the Novolizer^® compared to inhalation through the Turbuhaler^®. The Turbuhaler^® data, but not the Novolizer^® data, showed a significant negative correlation between lung function and inspiratory flow. The dynamic resistance of the Turbuhaler^® was 5.5-times higher than that of the Novolizer^®. Patients using the Turbuhaler^® had to invest a significantly higher inspiratory effort compared to the use of the Novolizer^® in order to achieve the same inspiratory flow (e.g., 60l/min). Indeed, more than 40% of the patients in the Turbuhaler^® group failed to reach an inspiratory flow of 60l/min. Overall, patients inhaling through the Novolizer^® had a better inhalation performance than those inhaling through the Turbuhaler^®.